The Longest Word In the World: Examples, Definitions, and More

The world is a big place full of big words. This is especially true in English, which is the primary language used for science. When a researcher makes a new discovery, they may have to create a new word to define or describe it. Often times, these words can get pretty long. However, there are also some very long English words that are not technical or scientific in nature. In any case, dozens of unique words compete for “the longest word in the world” title, so let’s take a look at the contestants!

The 10 Longest Words in English

Many experts argue over which words should or should not count when determining the longest word in English. For example, some say that it should be the word with the most letters, regardless of the word’s meaning or usage. Others claim that only non-technical, commonly used terms should qualify. Still, others believe that word length should depend on the number of syllables, as opposed to the number of letters. 

Finally, most people agree that hyphenated words (i.e. terms that combine two or more words with a dash) should not be included. For example, you could say that the term great-great-great-great-great-great-great-great-grandfather is the longest word in English. However, all you’d have to do to make it longer is add another great!

In any case, the following list of the 10 longest words in English will focus on the letter count. Later on, we will discuss some long words that might not make it in the top ten based on letter count, but might still be considered some of the longest words around. So, without further ado, let’s look at the top candidates for the longest word in the world!

Methionylthreonylthreonylglutaminylarginyl…isoleucine (189819 letters, ? syllables)

That’s right, there is a 189819 letter word in the English language! It’s unclear how many syllables the word has, but needless to say, we don’t have room to write out the entire word here! Fortunately, this is just the chemical name for a unique protein that is also known as Titin. If you’d like to know what the word sounds like, you can listen to a computer pronounce it in this hour-long video!

While this is the most “famous” of the long chemical names in the English language, it is not alone. For example, there are virtually endless combinations of chemical compounds that can be combined to form the name of a single strand of DNA. So, in theory, there are English words out there with more than a billion letters!

Methionylglutaminylarginyltyrosylglutamyl…serine (1909 letters, ? syllables)

Despite being another chemical name, this word makes the list because it is the longest published word in English. Originally published in a dictionary for students, this word is simply the scientific name for a particular strain of E. Coli. While it may not take as long to say as the previous word on this list, you’re still unlikely to hear it any time soon!

Lopadotemachoselachogaleokranioleipsano…pterygon (182 letters, 78 syllables)

This candidate for the longest word in the world originated from a Greek play written by Aristophanes in 391 BC. To this day, it remains the longest word in Ancient Greek literature. While the original Greek word contained 171 letters, it’s English translation contains a whopping 182 letters. However, it’s unlikely that you’ll use this word any time soon, as it refers to a fictional dish comprised of rotted dogfish head, wood pigeon, and dozens of other strange ingredients!

Pneumonoultramicroscopicsilicovolcanoconiosis (45 letters, 17 syllables)

Now we’ve come to words that you’ll actually see in an English dictionary. Still, this behemoth has almost twice as many letters as there are in the English alphabet! However, it’s definitely not the kind of word you’ll hear in everyday conversation. Nonetheless, it is, by most standards, the longest word in English and the longest word in the world! This word refers to a lung disease that can occur from inhaling small volcanic particles. So, how do you say pneumonoultramicroscopicsilicovolcanoconiosis? Very slowly.

Hippopotomonstrosesquippedaliophobia (36 letters, 14 syllables)

This is one of the most commonly referenced terms in the competition for the longest word in the world. Why? Because it literally means “a fear of long words!” Whoever created this term must have had a twisted sense of humor!

Pseudopseudohypoparathyroidism (30 letters, 12 syllables)

Finally, we’ve arrived at long words that people can actually pronounce! Nonetheless, for ease of use in medical writings, this term is often shortened to PPHP. It refers to a condition that causes irregular bone growth.

Floccinaucinihilipilification (29 letters, 12 syllables)

In many circles, floccinaucinihilipilification counts as the longest word in the world because it is the longest non-technical word in the English dictionary. In other words, you could actually find this word in a dictionary AND use it outside of a medical or scientific setting. The term refers to the action of finding something worthless.

Antidisestablishmentarianism (28 letters, 12 syllables)

Here’s another word that you might hear people throw around in a casual conversation. In addition to being easier to pronounce than most other words on this list, antidisestablishmentarianism is also a non-technical term. It refers to the belief that a State church should receive funding from the government. Due to its popularity as a fun word to say, many people (mistakenly) believe that it is the longest word in the world.

Honorificabilitudinitatibus (27 letters, 13 syllables)

Despite its length, honorificabilitudinitatibus has a pretty straightforward meaning. The word simply refers to the state of being honorable. So, the next time you want to hand out a compliment and flex your vocabulary skills at the same time, just use honorificabilitudinitatibus!

Thyroparathyroidectomized (25 letters, 9 syllables)

We end our list of the 10 longest words in English with one more medical term. This word refers to the excision of both the thyroid and parathyroid glands. Like many of the words on this list, you’re unlikely to hear this one outside of a medical setting.

The Longest Words in the World by Category

Though the list above shows the 10 longest words in English based on the traditional requirements (i.e. letter count), there are other methods for determining the longest word. So, let’s take a look at a few of the terms that could be considered the longest word in the world based on other criteria:

  • The longest word in the world based on letter AND syllable count:
    • Methionylthreonylthreonylglutaminylarginyl…isoleucine
  • The longest word in the world to be published:
    • Methionylglutaminylarginyltyrosylglutamyl…serine
  • The longest non-technical word:
    • Floccinaucinihilipilification
  • The longest isogram (word in which every letter is used only once) in the world:
    • Subdermatoglyphic
  • The longest recognized “nonsense” word:
    • Supercalifragilisticexpialidocious
  • The longest one syllable word in the world:
    • Scraunched


As you can see, determining the longest word in the world or the longest word in English is no easy task. Many people don’t count technical terms, but even if you do, the words can get so long that they cannot be feasibly written down or pronounced! In any case, learning one or two of these words will definitely help you sound a lot smarter when speaking English!

In closing, we hope you enjoyed this list of the longest words in the world! As always, for all things English conversation, grammar, or job-related, visit Magoosh Speaking today!

Matthew Jones

Matthew Jones

Matthew Jones is a freelance writer and former English teacher. He enjoys traveling the world, watching movies, and caring for his three toy poodles.
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